/Engine/Source/Runtime/NavigationSystem/Public/NavigationDataHandler.h
Removes associated NavOctreeElement and invalidates associated pending updates. Also removes object from the list of children of the NavigationParent, if any.
True if associated NavOctreeElement has been removed or pending update has been invalidated; false otherwise.
bool UnregisterNavOctreeElement ( [UObject](API\Runtime\CoreUObject\UObject\UObject) & ElementOwner, [INavRelevantInterface](API\Runtime\Engine\AI\Navigation\INavRelevantInterface) & ElementInterface, int32 UpdateFlags )